Oh yeah! Rated 4 out of 5 stars
Awesome except for that direction complaint. It's a developer thing, they just don't get usability sometimes. There is another add-on extension called "Tab Wheel Scroll" https://addons.mozilla.org/en-US/firefox/addon/6501 that does the same thing but is limited to scrolling within the tab bar area (not so bad) and it defaults to down going left too!! However it has a UI to be able to select your preference like this one really should too.
I'm in the process of attempting to modify the js code in this one and then update the xpi file. The only problem since I'm not a developer or programmer, is that the .jar file will not update after I modify it within the extracted xpi file (unlike rdf files which update easily . It simply reverts to the original code and date. The code appears simple enough to modify and if I can update the jar file and xpi file then I can at least install and test it to see if I can get this add-on to change the default behavior to the direction most of us seem to prefer. Don't hold your breath though.!